A Geomagnetic Smallsat Observatory for Operation in a 200 km Altitude Low Earth Orbit

An altitude of 200 km can improve the accuracy of measurements of the earth's crustal fields and low altitude ionospheric currents. However, atmospheric drag at this altitude requires altitude maintenance to provide useful orbital lifetime. In this study, a small-satellite conceptual design is developed to meet those requirements. The box shaped satellite basic configuration consists of science and electronics module mounted above a propulsion module. Overall satellite body size is 0.71 m x 0.71 m x 1.58 m long. The science and electronics module accommodates an 8 meter long deployable, non-magnetic boom carrying a scalar magnetometer, a star imager and a compact spherical coil magnetometer. Also mounted in this module are the modular electronic boxes, the NiH2 battery, a charged particle detector, and a position receiver utilizing both the GPS and the GLONASS systems. Major design drivers are the need to minimize the 'ram' area to reduce the amount of propellant for altitude maintenance, coupled with the requirement to accommodate the satellite within the volume and mass constraints of the Pegasus XL launch vehicle. With the chosen configuration the 'ram' area is reduced to 0.5 m2, using one flight proven propellant tank. The total wet mass of the satellite is 264 kg including margin.